I changed the tympan paper three days ago, and since then my grippers are not functioning properly.

When I press the gripper pedal the grippers go up, but when I release the pedal 3 out of 4 grippers remain up, and therefore are not gripping my paper at the feed board. Because I am printing a job, I’ve been manually pushing the grippers back down with my fingers so that they grip my paper.

What could be going on? Does the fact that one of the four grippers is actually functioning give a clue to what is wrong?

Someone suggested that perhaps the grippers need to be properly lubricated with graphite powder.

Any ideas I can try? I am not so good with press part names/technology yet, so please be as detailed as possible.

Thank you!!!!

4 thoughts on “Help! SP15 Grippers go up, but do not go down!”

  1. Paul, I followed your directions to a T and it solved the problem. Grippers are working perfectly. Thanks!

  2. There are many opinions on solvents. Mineral spirits are serviceable in most cases. For heavy degreasing, I reservedly recommend Simple Green. It is water-based, so it can cause rust to form if left unattended.

    Its advertised environmental friendliness and non-toxicity has been criticized, but has been EPA approved for oil clean ups (http://en.wikipedia.org/wiki/Simple_Green). Like mineral spirits, which is moderately toxic to aquatic organisms, is unlikely to present significant hazards to the environment. It should not be poured down the sink or freshwater drain.

    From the MSDS:

    National Fire Protection Association (NFPA) rating
    Health: 1 Flammability: 2 Reactivity: 0 — Mineral spirits
    Health: 1 Flammability: 0 Reactivity: 0 — Simple Green

    There are many more degreasers available and perhaps other commenters will join the conversation.

  3. Paul,

    Thank you very much for your concise and easy to follow instructions! As they seem straight forward I will bravely try to follow them.

    At the risk of asking an elementary question: how or what should I clean the pins and screws with?

    Better yet, besides the graphite and Vaseline, what cleaning agents/meterials do I need on hand to complete this task?

    Thanks so much! (And I will see you at your class in SF in January!)

    Bethany

  4. The gripper pins should be removed from gripper bar and cleaned before applying lubrication.

    At the feed board remove the draw sheet and packing, then retighten the gripper bar screws.
    Roll carriage to middle of bed so that gripper bar is on its back and screws face up.
    Remove screws and gripper bar from carriage.
    Clean and inspect threads on screws (NR-221).
    Working on one pin at a time, use a small screwdriver to pop out retainer clip at bottom of pin.
    Remove spring and push pin into bar until head of pin can be grasped and pulled out.
    Thoroughly clean and dry shaft of pin and underside of head.
    File burrs on underside of head which could damage paper.
    Clean pin holes on gripper bar and top of bar.

    Note that gripper bar and pin heads of pins have a matted appearance. This is a zinc coating that protects the bar from rusting. If scrubbing is necessary, use a scouring pad (e.g. Scotch Brite) and not steel wool.

    Reinstall pin into hole on gripper bar, add powdered graphite to lower half of shaft, then slide pin back a forth in hole a few times to distribute. Reinstall spring and retainer clip.
    Push pin into bar from bottom then wipe away any graphite that has worked its way to top of bar and underside of gripper head.

    At this point it’s a good opportunity to inspect the end guide assembly. Look for missing or broken copper paper guides (LB-7), split end guides (X-14696 ) or bent adjusting knobs (X-14565).

    Clean cams (X-21813) on push rod shaft.

    After all pins are reinstalled, add a small amount of Vaseline to bottom of pins

    This procedure is applicable to all SP series presses as well as later Universals.

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